Nozzles used to apply fluent material such as concrete, mortar or the like typically include a cylindrical housing through which the material is pumped, sped by the introduction of compressed air at one location along the nozzle. In order to further increase the speed of the material as it leaves the nozzle, a converging region is typically employed to increase the pressure within the material just prior to a nozzle exit port, resulting in a frusto-conical chamber. The resultant material distribution after exiting the nozzle is highly concentrated along an axis defined by the cylindrical nozzle. Such a concentrated distribution is necessary for applications where the nozzle projects the material at high speeds more than a minimal distance onto a surface to be covered.
Typical situations in which such nozzles are employed involve application of fluent material to a wall by manual manipulation of the nozzle, much akin to the direction of a stream of water by a fire fighter. In typical construction situations, these material applications must cover walls of twenty feet in height, or more. It is difficult to provide a consistent depth of concrete over a significant portion of the wall using such a manually operated and directed nozzle. In pursuit of a consistent application of fluent material to a desired depth on all portions of a wall surface, it is necessary to manually manipulate the nozzle such that a significant amount of overlap occurs. This results in over-application of fluent material at most regions and therefore the wasting of the over-applied material. This further necessitates an involved procedure for removal of the excess.
It is common practice to employ teams of manual laborers to draw trowels, sometimes of considerable size, over such manually over-applied surfaces of concrete or plaster. In situations involving high walls, scaffolding or hydraulic lifts must be provided to enable such hand trowelling. This practice is quite obviously time consuming and labor-intensive, and therefore expensive, while still posing a challenge in the provision of even finishes over large surfaces.
Therefore, presently available nozzles and material delivery systems fail to provide an even distribution of fluent material at a nozzle exit along at least one dimension. Further, these nozzles require inaccurate manual manipulation, resulting in inefficient application of the fluent material on a wall surface and necessitating time-consuming and expensive removal of excess.